1. Field of the invention
The present invention is generally concerned with contour follower devices which can "read" any shape and is more particularly, but not exclusively, directed to reading off the contour of the rims or surrounds of any eyeglass frame for the purpose of trimming lenses to be fitted thereto.
For example, and equally non-exclusively, the present invention is directed to the case where polar coordinates are used and the contour follower device comprises a support table fitted with holding means adapted to support the article whose contour is to be read off and a feeler with a contact head to be applied to the article and carried by a carriage which can reciprocate along a straight line path on the support, with rotation means for relative rotation between the support table and the carriage support.
2. Description of the prior art
A contour follower device of this type is described in European Patent Application No 0 181 788, for example.
Although it has been proposed to mount the contact head of the feeler rotatably, it is usually fixed.
This is the case in the above-mentioned European Patent Application No 0 181 788.
With currently known contour follower devices of this kind it is not rare for malfunctions to occur due to localized jamming of the feeler against the article whose contour is to be read off, especially if this contour has very tight corners, as can be the case with the rims or surrounds of some eyeglass frames.
This risk is accentuated if the contact pressure between the feeler and the article is high, as can be the case if it is produced by a spring whose tension varies with its length, as in European Patent Application No 0 181 788.
A general object of the present invention is to provide a very simple way of circumventing these disadvantages.